The loco gene and its effect on male fertility. A: The loco gene is comprised of nine exons. The final three exons, exon 2, 3 and 4 are common to all loco transcripts whereas the 5'exons are alternatively spliced to give rise to five different loco transcripts; loco c1 (AF130745), loco c2 (AF130744), loco c3, (AF245455), loco c4 (CG5248 PC) and loco c5 (AI944917). The exon numbers are shown below the genomic sequence and the conserved domains of the LOCO protein and the primers used to identify the transcripts in the testis and pupae are marked above the appropriate exons. Black regions indicate coding sequence, white regions represent untranslated regions. The P element in the original P insertion line, c139, is 322 bp upstream of exon 2. The loco318 mutant contains two P elements (or one P element and a partial P element) in reverse orientation 322 bp upstream of exon 2. The P elements of loco318 are flanked by a 9 bp duplication of genomic sequence. B: The sequence surrounding the P element insertion site in c139 was sequenced in loco358 and loco387 and aligned to the genomic DNA using ClustalW  and BoxShade . No deletion was observed. The region of genomic DNA that is duplicated in loco318 is highlighted in red. C: Hemizygous flies, containing the loco mutation and the deficiency chromosome (Df(3R)15CE1 (Df15), Df(3R)17D1 (Df17), or locoΔ13 ) or the wild-type, OrR, chromosome, were crossed with OrR, Df15, Df17 or locoΔ13 virgin females. The ratio between the total number of eggs laid and the number of eggs which hatched is represented as a percentage. Chi squared values were calculated by comparing the heterozygous male semi-steriles to OrR and the hemizygous mutants to the heterozygous deficiency lines. Chi squared values over 6.64 suggest that the reduction in fertility is due to the two lines being closely linked. Asterisks indicate a statistically significant reduction.
McGurk et al. BMC Developmental Biology 2008 8:37 doi:10.1186/1471-213X-8-37